Top climate scientist James Hansen tells the story of his involvement in the science of and debate over global climate change. In doing so he outlines the overwhelming evidence that change is happening and why that makes him deeply worried.

The NRA has fought to keep poisonous lead ammunition on the shelves -- spreading misinformation and attacking Sierra Club supporters, scientists, and even zoos. Now the NRA's launching its biggest attack yet, pushing an extremist bill that would strip

These bills would weaken protections offered by the Marine Mammal Protection Act and Toxic Substances Control Act, and would interfere with the authority of federal agencies responsible for managing natural resources. Included in the bills' language are